Fig. 1 shows a section through a flower from a rare orchid grown in a botanic garden. A gardener transferred pollen from the anther of one plant to the stig...
Question 1 Report
Fig. 1 shows a section through a flower from a rare orchid grown in a botanic garden. A gardener transferred pollen from the anther of one plant to the stigma of a second plant of the same species. The flower was then covered with a fine mesh cap so that insects could not add pollen from other flowers. Structure X is the stigma and structure Y is an ovule inside the ovary. The gardener wants to collect seeds from this flower for a conservation programme.
(a) What is the function of structure X during pollination? [1]
(b) Describe what happens between pollen landing on X and fertilisation of the ovule Y. [2]
(c) Give one advantage of using pollen from a different orchid plant rather than pollen from the same flower. [1]
Answer Details
(a) Structure X, the stigma, receives pollen grains or provides the surface on which pollen lands. [1]
(b) A pollen grain germinates and grows a pollen tube down the style [1]. The male nucleus or male gamete travels down this tube and fuses with the egg nucleus in the ovule [1]. This fusion is fertilisation.
(c) Pollen from a different orchid plant increases genetic variation in the offspring, reducing the risk of inbreeding. [1]
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